1. Field of the Invention
The invention concerns a method for whitening teeth which removes stain and leaves surfaces brighter.
2. The Related Art
People to some extent are judged by their smile. It is little wonder then that people are concerned with the appearance of their teeth. Stained ugly surfaces detract from the warmth intended to be conveyed by the smile. Stains arise from certain foods, tartar buildup, side effects of medicine and most especially smoking.
Abrasives in dentifrices are a first line of defense in combatting stains. Usually they deliver adequate but not superlative performance. An additional drawback is that abrasives, especially in higher concentrations, may damage enamel. Certain types of stains like those arising from smoking are often not removed by abrasive action alone.
Peroxides have been suggested as whitening agents. Unless employed at relatively high levels and in the presence of a catalyst, the peroxides are only modestly efficient in bleaching enamel.
Oral compositions with peroxide and baking soda (i.e. sodium bicarbonate) have become commercially quite popular. The combination of actives has been reported to promote healthy gums. When in contact, peroxide and baking soda are reactive towards one another. Therefore these ingredients must be maintained separately until time of use. Dispensing packages have been developed which physically isolate peroxide and baking soda by separating them into different compartments. This approach has been described in a series of patents to Schaeffer including U.S. Pat. No. 4,849,213, U.S. Pat. No. 4,528,180 and U.S. Pat. No. 4,687,663. Products based on this technology have been commercially sold in the United States under the Mentadent.RTM. brand of Peroxide and Baking Soda toothpastes. Mentadent.RTM. has been promoted for its gum care and antitartar properties. Hitherto there had been no indication that this product had any special effectiveness in whitening teeth. Variants of the Mentadent.RTM. brand toothpaste ranged in pH from about 7.5 to about 8.5 for a mixture of equal volume streams peroxide and baking soda.
It is an object of the present invention to provide a method for treating teeth to enhance their whiteness.
Another object of the present invention is to provide a method for whitening teeth which achieves its affect more rapidly than other previously known procedures.
Still another object of the present invention is to provide a method for whitening teeth employing relatively low levels of water-insoluble abrasives.
These and other objects of the present invention will become more readily apparent from consideration of the following summary and detailed discussion.